ffi/trap.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3
   4 #include "../debug.h"
   5
   6 /* TODO(bernhard): use {u,}int* types */
   7
   8 #define __USE_GNU
   9 // Note by hs: my signal.h includes sys/uconctext which conflicts with
  10 // asm/ucontext - this hack kinda solves the problem for me ;-)
  11 // so feel free to blame me for that s**t
  12 #if defined __USE_XOPEN2K8
  13 #undef __USE_XOPEN2K8
  14 #define RESTORE
  15 #warning hs-hack: undefining __USE_XOPEN2K8 for signal.h
  16 #endif
  17 #include <signal.h>
  18 #ifdef RESTORE
  19 #define __USE_XOPEN2K8
  20 #endif
  21
  22 #include <sys/ucontext.h>
  23
  24 unsigned int getMethodEntry(unsigned int, unsigned int);
  25 unsigned int getStaticFieldAddr(unsigned int);
  26 unsigned int getTrapType(unsigned int, unsigned int);
  27 unsigned int mallocObject(int);
  28
  29 #ifdef DBG_TRAP
  30 #define dprintf(args...) do { printf (args); } while (0);
  31 #else
  32 #define dprintf(args...)
  33 #endif
  34
  35 #define NEW_MAP(prefix) \
  36         void* prefix ## _map = NULL; \
  37         void set_ ## prefix ## map(void *map) \
  38         { \
  39                 dprintf("set_%s: 0x%08x\n", #prefix , (unsigned int) map); \
  40                 prefix ## _map = map; \
  41         } \
  42         void *get_ ## prefix ## map() \
  43         { \
  44                 dprintf("get_%s: 0x%08x\n", #prefix , (unsigned int) prefix ## _map); \
  45                 return prefix ## _map; \
  46         }
  47
  48 NEW_MAP(method)
  49 NEW_MAP(trap)
  50 NEW_MAP(class)
  51 NEW_MAP(virtual)
  52 NEW_MAP(strings)
  53 NEW_MAP(interfaces)
  54 NEW_MAP(interfacemethod)
  55
  56
  57 void mainresult(unsigned int a)
  58 {
  59         dprintf("mainresult: 0x%08x\n", a);
  60 }
  61
  62 void staticcalltrap(int nSignal, siginfo_t *info, void *ctx)
  63 {
  64         mcontext_t *mctx = &((ucontext_t *) ctx)->uc_mcontext;
  65         unsigned int from = (unsigned int) mctx->gregs[REG_EIP] - 2;
  66         unsigned int *to_patch = (unsigned int *) (from + 1);
  67         dprintf("callertrap(mctx)  by 0x%08x\n", from);
  68         if (*to_patch != 0x90ffff90) {
  69                 dprintf("callertrap: something is wrong here. abort\n");
  70                 exit(0);
  71         }
  72         unsigned int patchme = getMethodEntry(from, 0);
  73
  74         unsigned char *insn = (unsigned char *) from;
  75         *insn = 0xe8; // call opcode
  76         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
  77         dprintf("*to_patch: 0x%08x\n", *to_patch);
  78         *to_patch = patchme - (from + 5);
  79         dprintf("*to_patch: 0x%08x\n", *to_patch);
  80         mctx->gregs[REG_EIP] = (unsigned long) insn;
  81 }
  82
  83 void sigsegvtrap(int nSignal, siginfo_t *info, void *ctx)
  84 {
  85         mcontext_t *mctx = &((ucontext_t *) ctx)->uc_mcontext;
  86         unsigned int from = (unsigned int) mctx->gregs[REG_EIP];
  87         unsigned int *esp = (unsigned int *) mctx->gregs[REG_ESP];
  88
  89         /* if from is not *the* eip: get actual eip from stack storage */
  90         unsigned int from_stack = (*esp) - 3;
  91         switch(getTrapType(from, from_stack)) {
  92                 default: case 0: {
  93                         dprintf("something is wrong here: abort\n");
  94                         exit(1);
  95                 } break;
  96                 case 1: { // invokevirtual
  97                         if (from > 0) {
  98                                 dprintf("from: 0x%08x but should be 0 :-(\n", from);
  99                         }
 100                         unsigned int method_table_ptr = (unsigned int) mctx->gregs[REG_EAX];
 101                         unsigned char offset = *((unsigned char *) (*esp) - 1);
 102                         /* method entry to patch */
 103                         unsigned int *to_patch = (unsigned int*) (method_table_ptr + offset);
 104                         dprintf("invokevirtual by 0x%08x with offset 0x%08x\n", from_stack, offset);
 105                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 106                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 107                         *to_patch = getMethodEntry(from_stack, method_table_ptr);
 108                         mctx->gregs[REG_EIP] = *to_patch;
 109                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 110                 } break;
 111                 case 4: { // invokeinterface
 112                         if (from > 0) {
 113                                 dprintf("from: 0x%08x but should be 0 :-(\n", from);
 114                         }
 115                         unsigned int method_table_ptr = (unsigned int) mctx->gregs[REG_EAX];
 116                         unsigned int interface_table_ptr = (unsigned int) mctx->gregs[REG_EBX];
 117                         unsigned char offset = *((unsigned char *) (*esp) - 1);
 118                         /* interface entry to patch */
 119                         unsigned int *to_patch = (unsigned int*) (interface_table_ptr + offset);
 120                         dprintf("invokeinterface by 0x%08x with offset 0x%08x\n", from_stack, offset);
 121                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 122                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 123                         *to_patch = getMethodEntry(from_stack, method_table_ptr);
 124                         mctx->gregs[REG_EIP] = *to_patch;
 125                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 126                 } break;
 127                 case 2: { // static field patch
 128                         unsigned int *to_patch = (unsigned int *) (from + 2);
 129                         dprintf("staticfieldtrap by 0x%08x\n", from);
 130                         if (*to_patch != 0x00000000) {
 131                                 dprintf("staticfieldtrap: something is wrong here. abort\n");
 132                                 exit(0);
 133                         }
 134                         unsigned int patchme = getStaticFieldAddr(from);
 135
 136                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 137                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 138                         *to_patch = patchme;
 139                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 140                 } break;
 141         }
 142 }
 143
 144 void register_signal(void)
 145 {
 146         struct sigaction illaction;
 147         illaction.sa_sigaction = staticcalltrap;
 148         sigemptyset(&illaction.sa_mask);
 149         illaction.sa_flags = SA_SIGINFO | SA_RESTART | SA_NODEFER;
 150         sigaction(SIGILL, &illaction, NULL);
 151
 152         struct sigaction segvaction;
 153         segvaction.sa_sigaction = sigsegvtrap;
 154         sigemptyset(&segvaction.sa_mask);
 155         segvaction.sa_flags = SA_SIGINFO | SA_RESTART | SA_NODEFER;
 156         sigaction(SIGSEGV, &segvaction, NULL);
 157 }
 158
 159 unsigned int getaddr(void)
 160 {
 161         return (unsigned int) mainresult;
 162 }
 163
 164 unsigned int getMallocObjectAddr(void)
 165 {
 166         return (unsigned int) mallocObject;
 167 }